Gravity safety switch

ABSTRACT

A gravity operated switch includes a movable electrically conductive member in a housing. The conductive member bridges a pair of fixed spaced electrical contacts. When the housing is tilted the movable conductive member moves off or out of contact with the electrical contacts to open an associated electric circuit. The switch has particular utility in tractors and other machines to stop operation when the machine is tilted to an unsafe operating position. The switches control flow of fuel to the engines of the machines, ignition, or other engine control components.

1111mm States Patent [72] Inventor Benjamin F. Hughes Route 1, Box 120, Morris, Ala. 35116 [21] Appl. No. 845,278 I211 Filed July 28,1969 14%| l'zllrnlt'll Aug. [7,1971

[54] GRAVlTY SAFETY SWITCH 10 C1aims, 31 Drawing Figs.

[52] 1.1.5.111. 180/104, 180/101, ZOO/61.47, ZOO/61.48, 200/61.52 [51] int. Cl. ..H01h35/02, B60k 15/00 [50] Field 01' Search 180/104, 103,114;200/61.45, 61.47, 61.52

[56] References Cited UNITED STATES PATENTS 2,192,262 3/1940 Griesedieck 180/104 X 1,996,836 4/1935 Sevison ZOO/61.47 2,100,105 11/1937 Lee etal. ZOO/6147 2,503,449 4/1950 Murray..... 180/104 3,303,836 2/1967 Burleigh 180/114 I'rimury lz'xamim'r-l.co Friaglia Assistant Examiner-John P. Silverstrim AllurneyPolachek 8L Saulsbury PATENTED AUG 1 7 m.

SHEET 0F Q T'romvm PATENTEU AUG] 7 19?:

SHEET M [1F 1 "mvrcmvm.

GRAVITY SAFETY SWITCH The invention is particularly directed at a gravity operated switch which responds to the angular position assumed by the switch with respect to a normal horizontal position.

According to the invention a metallic ball or a globule of mercury is supported on a seat in a switch housing. The housing may have multiple angularly disposed arms or may be circular. At the seat are spaced electrical contacts which may be connected to an external electric circuit. The ball mechanically and electrically bridges the contacts. The housing is normally disposed in a horizontal position with the ball on the seat. When the housing is tilted sufficiently in any direction, the ball rolls off the seat into a pocket or recess where it is retained. This breaks the external electric circuit leaving the contacts open. The ball is retained in the pocket or recess and does not return automatically to the seat when the switch again assumes a horizontal position. The ball is returned to the seat by inverting or otherwise turning or manipulating the switch. In a modification of the invention, the movable conductive member is supported like a pendulum in a switch housing. The pendulum is displaced when the switch is tilted and is held displaced by a magnet in the housing. The magnet is ring shaped or has a horse shoe shape. The pendulum can be restored to normal position by manually manipulating the pendulum. Switches embodying the invention can be applied to safeguard tractors subject to tilting an unsafe operating angle, and such usage is described below.

The invention will be explained in further detail in conjunction with the drawings, wherein: FIG. 1 is an oblique top view ofa first switch embodying the invention.

FIG. 2 is an end elevational view taken on line 2-2 of FIG. 1.

FIG. 3 is a side elevational view taken on line 3-3 FIG. 2.

FIG. 4 is a horizontal cross-sectional view taken on line 4-4 of FIG. 2.

FIG. 5 is a vertical sectional view taken on line 5-5 of FIG. 1.

FIG. 6 is a bottom plan view taken on line 6-6 of FIG. 2.

FIG. 7 is a cross-sectional view taken on line 7-7 of FIG. 1.

FIG. 8 is a top plan view of a second switch embodying the invention.

FIG. 9 is a vertical sectional view taken on line 9-9 of FIG. 8.

FIG. 10 is an end elevational FIG. 8.

FIG. 11 is an end elevational view similar to FIG. 2 ofa third switch embodying the invention.

FIG. 12 is a horizontal sectional view taken on line 12-12 of FIG. 11.

FIG. 13 is a side elevational view ofa fourth switch.

FIG. 14 is a top plan view of the switch of FIG. 13.

FIG. 15 is a vertical sectional view taken on line 15-15 of FIG. 14.

FIG. 16 is a horizontal cross sectional view taken on line 16-16 of FIG. 15.

FIG. 17. is a view similar to FIG. 15 showing the switch in a tilted position.

FIG. 18 is a perspective view ofa fifth switch.

FIG. 19 is a vertical sectional view on an enlarged scale taken on line 19-19.

FIG. 20 is a horizontal sectional view taken on line 20-20 of FIG. 19.

FIG. 21 shows a first circuit employing a gravity switch for protecting a tractor by cutting off fuel supply ofits engine.

FIG. 22 shows a second circuit employing a gravity switch for protecting a tractor powered by employing a diesel engine.

FIG. 23 is a sectional view showing details of a seat switch employed in the circuits of FIGS. 21,22.

FIG. 24 is a sectional view of a foot-operated switch employed in the circuits of FIGS. 21,22.

view taken on line 10-10 of FIG. 25 is a side view of a sixth switch generally similar to FIG. 13 showing a modification of the fourth gravity switch of FIG. 13.

FIG. 26 is a vertical sectional view of the sixth switch shown in FIG. 25.

FIG. 27 is a fragmentary cross-sectional view taken on line 27-27 of FIG. 26.

FIG. 28 is a vertical sectional view of a seventh switch similar to the switch of FIG. 19, but showing a modification thereof.

FIG. 29 is a horizontal cross-sectional view taken on line 29-29 of FIG. 28.

FIG. 30 is a diagram of a third circuit employing a gravity switch to control the ignition ofa tractor engine.

FIG. 31 is an enlarged sectional view of a mercury switch employed in the circuit of FIG. 30.

Referring first to FIGS. 1-7, there is shown a switch S1 having a housing 21 formed with three tubular arms or wings 22, 23, 24. The housing is made of insulative material and is sealed closed. Wings 22 and 23 are axially aligned with each other while wing 24 is axially perpendicular to the central axis of wings 22, 23. At the common intersection of the axes of the wings is a pocket 25 which serves as a seat for a globule of mercury 26. Instead of mercury a metal ball can be substituted. Projecting into pocket 25 is a pair of fixed electrical contacts 28. These contacts are provided with electrical leads 30 which extend outwardly of a projection 32 formed at the underside of pocket 25. Further pockets 33, 34 and 35 are formed at the bottoms of the ends of wings 22, 23 and 24 respectively.

Normally ball or globule 26 will seat in pocket 25 as shown in FIG. 5 when the switch is horizontal, that is when the axes of the three wings are all horizontal. If the switch is tilted from the horizontal beyond a predetermined angle as illustrated in FIG. 7, globule 26 rolls out of pocket 25 and into the pocket of the wing which extends angularly downward, into pocket 35 for example. If the switch is restored to normal horizontal position, the globule or ball will remain in the outer pocket 33, 34 or 35. To restore the globule or ball to pocket 25 the switch must be tilted downwardly as shown in FIG. 7, then it must be tilted upwardly to restore the ball as indicated by dotted lines in FIG. 7.

FIGS. 8, 9 and 10 show a second switch S2 which is generally similar to switch S1 and corresponding parts are identically numbered. In switch S2, the axes of wings 22, 23' are angularly disposed with respect to each other. The wings axially slant upwards from central pocket 25. Thus it will be necessary to tilt the switch more than would be required for switch S1 to displace globule or ball 26.

Switch S3 shown in FIGS. 11 and 12 is similar to switch S1 and corresponding parts are identically numbered. In switch S3 further pairs of spaced fixed contacts 36, 38 and 40 are provided in pockets 33, 34 and 35 at ends ofwings 22, 23 and 24 respectively. Thus when ball or globule 26 rolls out of pocket 25 it rolls into one of pockets 33, 34 and 35 to bridge the contacts therein. If an electrical circuit is connected externally to leads 43 of any one or more of the contact pairs 36, 38 or 40, this circuit will be closed. Thus the external circuit connected to fixed contacts 28 at pocket 25 will be opened while the circuit connected to contacts 36, 38 or 40 will be closed.

Switch S4 shown in FIGS. 13-l7 has a closed substantially hemispherical housing 50 made of insulative material. Inside the housing at the center thereof is an elevated table 52 formed with a concave seat 54 on top. A globule 26a of mercury seats normally in seat 54. Inside the seat projects a pair of fixed electrical contacts 56. Leads 58 extend outwardly at the bottom of the housing and can be connected to an external circuit. Concentrically surrounding table 52 is an annular groove 60 in which are set spaced concentric electrical conductive ring contacts 62. Leads 64 are connected to the rings and extend out at the bottom of the housing. The housing has an annular flange 66 pivotally supported on a pin 68 at posts 70 on a flat baseplate 72. The housing is supported on circumferentially spaced coil springs 74 through which extend bolts 76. The bolts extend through flange 66 and are engaged by nuts 78.

FIG. 17 shows how tilting the switch from the normal horizontal position of FIG. will cause the globule to flow down into groove 60 to bridge conductive contacts 62 and close any electric circuit connected thereto. If the switch is now set in a horizontal position the globule will remain in groove 60. To restore the globule to the position of FIG. 15, on seat 54, the entire switch must be inverted. Alternatively, the housing 50 can be inverted as indicated by dotted lines in FIG. 13. This can be done by removing nuts 78 and manually turning the housing on pin 68 through 180 degrees. The globule will then flow past the constricted space S between the rim of seat 54 and the adjacent inner side of the housing. Thereafter the housing can be turned quickly to the position of FIG. 15 and the globule will drop down on seat 54.

FIGS. 25, 26 and 27 show switch S6 which is generally similar to switch S4 and corresponding parts are identically numbered. In switch S6, the seat 54' is elongated radially in the forward travelling direction F of a tractor in which the switch will be installed. The top of the seat extends radially at portion 54 to the inside wall of hemispherical housing 50, to prevent the globule of mercury from rolling down into groove 60 when the tractor tilts down in the forward direction of travel. The housing 50 is formed on top with a spherically curved dome 50". This dome will receive the globule 26a when the hemisphere is inverted to flow out of groove 60. Then the globule will drop directly down on seat 54 when the housing is turned again to upright position.

FIGS. 18, 19 and show a switch S5 which has a cylindrical axially vertical insulative housing 80. A conductive screw shaft 82 has a ball 84 at its upper end 82 pivotal in an electrically conductive universal ring bearing 86 secured in a hole 87 at the top wall 88 of the housing. Shaft 82 projects outwardly beyond the top wall 88 through hole 87. Electrical lead 90 is connected to bearing 86 and extends radially outward of the housing. An electrically conductive disk 92 is adjustably sup ported on the shaft by nuts 93, 94. The disk is spaced inwardly of a cylindrical ring contact 96 mounted inside the cylindrical housing. Electrical lead 98 extends radially outward of the housing and is connected to ring contact 96. A spherical weight 100 is secured to the lower end of shaft 82 which constitutes a pendulum. Shaft 82 is electrically conductive. The weight is normally spaced inwardly of a ring magnet 102 secured to the inside of the housing.

If the switch housing is tilted axially from normal axially vertical position, the pendulum will tend to remain axially vertical and conductive disk will contact wing contact 96. This will close any electric circuit connected to leads 90 and 98. The magnet will attract and hold weight 100 so that when the switch housing is again disposed upright, the pendulum will be held in angularly deflected position by the magnet. The pendulum can be restored to vertical position by manually grasping and moving laterally the external end 82' of shaft 82. This will open the external circuit connected to contacts 90, 98 as disk 92 separates from ring contact 96.

FIGS. 28 and 29 show a seventh switch S7 which is a modification of switch S5. Parts corresponding to those of switch S5 are numbered identically. Switch S7 is shown in a tilted position in FIG. 29. In switch S7, magnet 102 is horseshoe shaped. The gap (1 at ends of the magnet is located in forward direction F in which the switch would be installed in a tractor.

When the tractor tilts downward forwardly magnet 102' does not grip ball 100. Contact 96' is cylindrically curved and is also horseshoe shaped so that when disk 92 moves forwardly it does not touch contact 96'. Lead 98' is connected to contact 96'. Leads 90 and 98' can thus be connected in an external circuit which will be normally open since the switch is normally open between leads 90 and 98 in all positions except the forward position. When the switch is tilted axially rearwardly as shown in FIG. 29, disk 92 will touch contact 96. A further spring contact 99 is mounted on the wall of insulative housing Lead 101 is connected to contact 99. This contact terminates in a ball 99 which normally touches disk 92. Thus an external circuit connected between leads and 101 will remain normally closed when the switch tilts axially forward because the ball will remain in contact with the disk. However if the switch tilts in other directions, disk 92 will separate from contact 99 as shown in FIG. 29 and the external circuit connected to contact 99 will open.

FIG. 21 shows schematically how a gravity switch S1 can be connected in a control circuit C1 for protecting a machine such as a tractor. Ball or globule 26 normally bridges contacts 28. One lead 30' is connected to coil of a solenoidoperated valve 112. The valve is located in the fuel supply line of the tractor. The valve is held open when the solenoid is energized. Lead 30" is connected to line 132, to contact 114 of a foot-operated switch 116 and to contact 118 of a seat switch 120. The other contact 122 of the foot switch is connected to line 133 which terminates at terminal 124 of battery 125. The other terminal 126 of the battery is grounded at its terminal 128 of coil 110. A manually operable switch 130 is connected across power lines 132, 133. Fixed contact 134 of the seat switch is connected to line 133. Details of the seat and foot switches are shown in FIGS. 23,24.

Normally globule or ball 26 bridges contacts 28. The driver sits on seat which closes seat switch 120. Thus solenoid coil 110 is energized and the solenoid valve 112 is held open permitting fuel to reach the engine via line 115. If the driver leaves seat 140, seat switch 120 opens and the solenoid valve becomes deenergized to close off fuel from the engine. If the driver steps on normally open foot switch 116 the same result occurs. If the tractor tilts excessively during operation, the gravity switch S1 mounted in the tractor tilts out of its normally horizontal position. Globule or ball 26 will become displaced from contacts 28 and the solenoid valve will become deenergized. This will cut off fuel from the tractors engine which will then stop. The engine will not be restarted even though the tractor and switch S1 reassume a horizontal position. It will be necessary to turn the switch on its mounting to restore the ball 26 to its seat at contacts 28. Any one of switches S2S5 can be substituted for switch S1 to obtain the same result.

Circuit C2 in FIG. 22 shows how switch S4 can be used for protecting a tractor. Parts corresponding to circuit C1 are identically numbered. Two solenoid-operated valves 112 and 112 are provided. Valve 112 is connected in main fuel supply line 115 leading to fuel injector pump 160. Valve 112 is connected in bypass drain line 162 leading from the pump back to the main line 115. Solenoid coil 110 serves to hold valve 112 open when the coil is energized as in circuit C1. Solenoid coil 110 serves to hold valve 112' open when this coil is energized. Coil 110 is connected to fixed contact 56. Coil 110' is connected to annular fixed contact 62. Annular contact 62' is connected to line 133. Contact 56 is grounded.

When the operator closes foot switch 116, or sits on seat switch 120 or manually closes switch 130 solenoid coil 110 is energized and valve 112 is energized to close valve 112 and pass fuel to the engine via normally open valve 112. If the tractor tilts, ball 26a leaves contacts 56, 56 and bridges contacts 62, 62. This causes valve 112' to be opened by energized solenoid coil 110' while valve 112 closes because coil 1 10 becomes deenergized. Excess pressure and fuel is drained back to line 115 via bypass line 162 and open valve 112'.

The valves remain in respective open and closed positions even though the tractor later assumes a safe horizontal position because ball or globule 26a remains in groove 60 as explained in connection with FIGS. 13-17.

Pendulum operated switch S5 or multiple wing and contact switch 53 can be substituted for switch S4 in circuit C2.

FIG. 30 shows another control circuit C3 which is arranged to cutoff power from the ignition ofa tractor engine when the tractor tilts at a dangerous angle. In circuit C3, seat 200 is mounted on springs 201. Underneath the seat is a mercury switch 202. As best shown in FIG. 31, switch 202 has a closed cylindrical casing 203 in which is mercury ball 205. The casing is secured pivotally by bars 204,206 at opposite ends to brackets 208,210 under the seat. Terminal contacts 212 and 214 of two wires 216, 218 are secured in the wall of casing 203 and are exposed inside the casing of switch 202. The switch is normally disposed in an axially upward tilted position. While the driver sits on seat 200 switch 202 is closed as ball 205 flows or rolls to contacts 212,214 to close the associated parts of circuit C3. Another mercury switch 202 identical to switch 202 is mounted in a foot'operated switch 220 under treadle 222 supported by springs 223, Switch 202' is disposed in a tilted normally open position and is connected in parallel with switch 202 to wires 214,216. While the foot of the driver is on treadle 222, switch 202' is closed. Manually operable switch 130 is also connected to wires 214,216, in parallel with switches 202 and 202. Gravity switch S1 is connected in series with the switches and with ignition coil 225 of the tractor engine. The high voltage output line 226 of coil 225 is connected to rotary contact 228 of distributor 230. Contacts 232 of the distributor are connected to spark plugs 234 of the engine of the tractor. Wire 214 is connected to battery 125 of the tractor. Either switch 202,202 or 130 must be closed for voltage to be applied to the ignition circuit of the tractors engine. If the tractor tilts at an unsafe angle, the ignition circuit will be opened by displacement of ball 26. In place of switch S1, any of switches S2S7 can be substituted. For example, if switch S7 is employed in place of switch S1, leads 90 and 101 will be connected between wire 216 and the ignition coil. If the tractor tilts down forwardly switch S7 will remain closed; but if the tractor tilts excessively at any other angle disk 92 will separate from contact 99 and switch 57 will open to open the ignition circuit and stop the tractors engine. The mercury switches 202 and 202' shown in FIG. 30 can be substituted for the seat and foot switches of circuits Cl and C2 if desired to minimize the corrosion at contact points which takes place in dry switches. The various gravity operated switches S1S7 can be used for other vehicles than tractors and in applications ofother types where required.

I claim:

1. A gravity switch combination for protecting a machine subject to tilting at an unsafe operating angle, comprising a housing mountable in a fixed position on said machine, a seat in said housing, an external circuit, a pair of fixed spaced electrical contacts at said seat connectable in said external electric circuit, an electrically conductive ball normally seated on said seat and bridging said contacts to close said circuit, and means for retaining said ball displaced from said contacts once the housing has been tilted to displace the ball from said seat, in which said housing comprises a plurality of tubular wings, said seat being a pocket centrally located with respect to said wings, the last named means comprising other pockets for receiving said ball at ends of the wings, and other spaced fixed contacts at said ends of the wings in said pockets, said other contacts being connectable in other external electrical circuits, any one of said other electrical circuits being closable when said ball is deposited in the pocket of one of the wings to bridge the contacts thereat.

2. A gravity switch combination for protecting a machine subject to tilting at an unsafe operating angle, comprising a housing mountable in a fixed position on said machine, a seat in said housing, an external circuit, a pair of fixed spaced electrical contacts at said seat connectable in said external electric circuit, an electrically conductive ball normally seated on said seat and bridging said contacts to close said circuit, and means for retaining said ball displaced from said contacts once the vehicle has been tilted to displace the ball from said seat and returned to a safe operating angle, and means selectively movably mounting the housing for restoring the ball to said seat, and other fixed spaced contacts located at the means for retaining the ball displaced from the first named contacts, said other contacts being connectable to another external electric circuit, whereby said first named external circuit is opened and the other external circuit is closed when the ball is displaced from the first named contacts and bridges said other contacts.

3. A gravity switch combination as defined by claim 2, wherein said ball is a globule of mercury.

4. A gravity switch combination as defined by claim 2, wherein said housing comprises a plurality of tubular wings, said seat being a pocket centrally located with respect to said wings, the last-named means comprising other pockets for receiving said ball at ends of the wings.

5. A gravity switch combination as defined by claim 4, wherein at least two of said wings are disposed at angles to each other for receiving the ball in one of the other pockets when the housing is tilted.

6. A gravity switch combination as defined by claim 2, wherein said housing is hemispherical in form and wherein the seat is centrally located so that the globule is displaced from the seat regardless of the direction in which the housing is tilted.

7. A gravity switch combination as defined by claim 6, wherein the means for retaining the globule when displaced from said seat is agroove surrounding the seat, said seat being elevated above said groove axially ofthe housing.

8. A gravity switch combination as defined by claim 7, further comprising spaced annular contacts in said groove disposed for bridging by said globule when the globule is displaced from said seat.

9. A gravity switch combination as defined by claim 2, wherein said first-named external circuit comprises a solenoid coil arranged to close a fuel supply line of said machine, said coil being connected to said contacts so that the coil is energized when the ball is on the seat and is deenergized when the ball is displaced from the seat.

10. A gravity switch combination as defined by claim 2, wherein the first-named external circuit is the ignition circuit of an engine said ignition circuit being connected to said contacts so that the ignition circuit is energized when the ball is on the seat and is deenergized when the ball is displaced from said seat. 

1. A gravity switch combination for protecting a machine subject to tilting at an unsafe operating angle, comprising a housing mountable in a fixed position on said machine, a seat in said housing, an external circuit, a pair of fixed spaced electrical contacts at said seat connectable in said external electric circuit, an electrically conductive ball normally seated on said seat and bridging said contacts to close said circuit, and means for retaining said ball displaced from said contacts once the housing has been tilted to displace the ball from said seat, in which said housing comprises a plurality of tubular wings, said seat being a pocket centrally located with respect to said wings, the last named means comprising other pockets for receiving said ball at ends of the wings, and other spaced fixed contacts at said ends of the wings in said pockets, said other contacts being connectable in other external electrical circuits, any one of said other electrical circuits being closable when said ball is deposited in the pocket of one of the wings to bridge the contacts thereat.
 2. A gravity switch combination for protecting a machine subject to tilting at an unsafe operating angle, comprising a housing mountable in a fixed position on said machine, a seat in said housing, an external circuit, a pair of fixed spaced electrical contacts at said seat connectable in said external electric circuit, an electrically conductive ball normally seated on said seat and bridging said contacts to close said circuit, and means for retaining said ball displaced from said contacts once the vehicle has been tilted to displace the ball from said seat and returned to a safe operating angle, and means selectively movably mounting the housing for restoring the ball to said seat, and other fixed spaced contacts located at the means for retaining the ball displaced from the first named contacts, said other contacts being connectable to another external electric circuit, whereby said first named external circuit is opened and the other external circuit is closed when the ball is displaced from the first named contacts and bridges said other contacts.
 3. A gravity switch combination as defined by claim 2, wherein said ball is a globule of mercury.
 4. A gravity switch combination as defined by claim 2, wherein said housing comprises a plurality of tubular wings, said seat being a pocket centrally located with respect to said wings, the last-named means comprising other pockets for receiving said ball at ends of the wings.
 5. A gravity switch combination as defined by claim 4, wherein at least two of said wings are disposed at angles to each other for receiving the ball in one of the other pockets when the housing is tilted.
 6. A gravity switch combination as defined by claim 2, wherein said housing is hemispherical in form and wherein the seat is centrally located so that the globule is displaced from the seat regardless of the direction in which the housing is tilted.
 7. A gravity switch combination as defined by claim 6, wherein the means for retaining the globule when displaced from said seat is a groove surrounding the seat, said seat being elevated above said groove axially of the housing.
 8. A gravity switch combination as defined by claim 7, further comprising spaced annular contacts in said groove disposed for bridging by said globule when the globule is displaced from said seat.
 9. A gravity switch combination as defined by claim 2, wherein said first-named external circuit comprises a solenoid coil arranged to close a fuel supply line of said machine, said coil being connected to saId contacts so that the coil is energized when the ball is on the seat and is deenergized when the ball is displaced from the seat.
 10. A gravity switch combination as defined by claim 2, wherein the first-named external circuit is the ignition circuit of an engine said ignition circuit being connected to said contacts so that the ignition circuit is energized when the ball is on the seat and is deenergized when the ball is displaced from said seat. 